Material handling machine



March 1963 D. M. SCHWARTZ ETAL 3, 0

MATERIAL HANDLING MACHINE 7 Sheets-Sheet 1 Original Filed March 29, 1955DA NIEL M .SCHWARTZ THEODORE N. HACKE TT, DUNCAN l. McCALLUM March 1963D. M. SCHWARTZ ETAL 3,

MATERIAL HANDLING MACHINE Original Filed March 29, 1955 '7 Sheets-Sheet2 :f I24 I30 "2 II I53" I22 I30 I34 I20 I H8 I25 "6" 5 I l i 5 if z 1I26 IIO r i Z i i g I I48 I40 I42 [54 IN VENTORS DANIEL M SCHWARTZTHEODORE N.HACKET'T, DUNCAN I. McCALLUM ATTORNEY March 1963 D. M.SCHWARTZ ETAL 3,

MATERIAL HANDLING MACHINE 7 Sheets-Sheet 3 Original Filed March 29, 1955m! w! v2 3mm DANIEL M. SCHWARTZ THEODORE N. HACKET'T,

DUNCAN I. McCALLUM. i M TM March 1963 D. M. SCHWARTZ ETAL 3,

MATERIAL HANDLING MACHINE Original Filed March 29, 1955 '7 Sheets-Sheet4 awe/Mow DANIEL M.SCHWARTZ THEODORE N.HACKETT, DUNCAN I. MCCALLUM.

e AMQ/ TM March 1963 D. M. SCHWARTZ ETAL 0 MATERIAL HANDLING MACHINE 7Sheets-Sheet 5 Original Filed March 29, 1955 INVENTOR$ DANIEL M.SCHWARTZ THEODORE N. HACKETT, DUNCANII. McCALLUM. BY /MW ATTORNEY March19, 1963 D. M. SCHWARTZ ETAL 3,081,890 MATERIAL HANDLING MACHINEOriginal Filed March 29,

ts-Shee 6 Ire INVENTORS DANIEL M. SCHWARTZ. THEODORE .HACKETT, DUNCANLMgCALLUM.

ATTORNEY March 19, 1963 D. M. SCHWARTZ E TAL 3,081,890

MATERIAL HANDLING MACHINE '7 Sheets-Sheet '7 Original Filed March 29,1955 wmm NNNJ mom ONN mmm

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INVENTORS DANIEL M. SCHWARTZ THEODORE N. HACKET l. Mc CALLUM DUNCAN BYA/M 7.14M

ATTORNEY United States Patent 3,681,890 MATERIAL HANDLING MACWE DanielM. Schwartz and Theodore N. Hackett, Sait Lake City, Utah, and Duncan I.Me'Callum, deceased, late of Mud Lake, Idaho, by Laurette C. Metlallum,administratrix, Montreal, Quebec, Canada, assignors, by mesneassignments, to The Eimeo (Importation, Salt Lake City, Utah, acorporation of Delaware Continuation of application Ser. No. 497,754,Mar. 29, 1955. This application Mar. 7, 1962, Ser. No. 178,531 7 Claims.(Cl. 214-131) This invention relates to a mobile material handlingmachine that is characterized by its compactness, mobility and ease ofcontrol. The invention will be particularly described with reference tosuch a machine including an overhead bucket supported on a main framehaving individually operated crawlers or self-laying tracks.

This application is a continuation of our copending application SerialNo. 497,754, now abandoned.

It is an object of the invention to provide such a machine having acentrally positioned prime mover, with a rear power take-off connectedto a material handling structure actuating mechanism.

A further object is to provide a bucket transmission which is of theconstant mesh hydraulically controllable type.

Another object is to provide such a device having an overhead bucketmaterial handling means wherein the overhead bucket mechanism isautomatically disconnected from the power supply and its travel reversedand/or stopped at substantially any predetermined bucket positionwhereby the discharge distance of the bucket may be readily controlled.

Another object is to provide brake mechanism for the overhead bucketmaterial handling device which is automatically applied and preventsfurther travel of the bucket when the bucket control lever is releasedintentionally or accidentally.

A further object is to provide a two-speed drive mechanism for theoverhead bucket device whereby extremely high digging force may beobtained in a low gear position, and high speed material discharge maybe obtained in the high speed gear position.

These and other objects and advantages of the invention will appear moreclearly from the detailed description in conjunction with theillustrative embodiments shown in the accompanying drawings in which:

FIG. 1 is a right front perspective view of the overhead materialhandling machine of the invention with the cab and the motor, andtransmission covers, and one of the rocker arms removed;

FIG. 2 is an enlarged fragmentary section of the over head bucket drivemechanism for clarity;

FIG. 3 is a view similar to that shown in FIG. 2 in partial section withthe control valve and cam actuating mechanism therefor rotated 90;

FIG. 4 is a view similar to that shown in FIG. 3 with the drive clutchesin the bucket-up low speed position;

FIG. 5 is an enlarged detailed view in partial section of the bucketpower cut-elf mechanism;

FIG. 6 is an enlarged framentary sectional view substantially on line6--6 of FIG. 5;

FIG. 7 is a fragmentary view substantially on line 77 of PEG. 6;

FIG. 8 is a diagrammatic representation of the hydraulic system of thematerial handling machine.

With particular reference to FIG. 1 of the drawings, there is shown amaterial handling apparatus generally embodying the principle of theinvention. While the 3,081,890 Patented Mar. 19, 1963 material handlingmachine shown in the drawings and described hereinafter has endlesschain type traction units, it will be evident that other forms oftraction units such as wheels could be used on the machine without lossof the objects and advantages of this invention. The machine has a mainframe consisting of three individual and separable sections comprising aforward section 10, a center section 12 and a rear section 14-.

The forward section 10 carries the constant mesh hydraulically actuatedtransmission 16 for the rear drive, endless track type traction units18.

The center section 12 carries a single prime mover 20, centrallypositioned therein, a hydraulic torque converter 22, and a pair oftorque shafts, one of which is designated 24 in FIG. 2, which arepositioned on either side of the prime mover 20.

The rear section 14 carries the opposed dual drives for the individuallyoperated crawlers in the lower section and an overhead bucket actuatingmechanism including a constant mesh hydraulically actuated buckettransmission, generally designated 32, positioned above the dual drives.

The forward transmission, as to be more fully described in ourapplication Serial No. 377,125, is connected to the prime mover througha universal coupling 34 to the torque converter 22, while the rear orbucket transmission 32 is connected to the same prime mover by means ofa rearwardly extending power take-off 36, belts 37 and belt sheaves 38and 40. A rear power takeoif shaft 41 extends rearwardly from shaft 36and rotates with sheaves 40.

On installations where the prime mover is of the Diesel or Otto cycleinternal combustion type, a coolant heat exchanger 42 for the engine ispositioned between the rearward extremity of the engine and the forwardextension of the bucket transmission.

As more clearly shown in FIG. 3, the bucket drive mechanism andtransmission is in itself a separate unit which merely bolts to the rearsection of the main frame. It will also be seen that the crawler drives28 and 3%) are each separate units which are bolted to a spacer frame 44to form the lower portion of the rear section 14.

The main frame of the material handling machine supports an overheadbucket assembly upon parallel tracks or rails 78 secured along each sideof the main frame,

The overhead bucket structure is of the overhead rocker type. The sideframes 80, only one of which is shown in the drawings, of the rockerstructure have curved outer surfaces for rolling engagement with theparallel rails 78, the radius of curvature of the surfaces generallyincreasing from the forward to the rearward ends of the curved sections.

Between the lower ends of the curved rocker arms is supported a shovelbucket 82 and each arm is also provided with a shock absorbing bumpermember 84 having a spring loaded piston 86 slidably mounted therein.Each piston contacts a corresponding plate 83 secured to a rigid bumperframe 90 mounted at the rear end of the main frame when the bucket is inthe dumping postion.

Flat cable chains 92, one for each rocker arm, are attached at one endto the rocker arms, as at 94, just above the bumper members 84 and theother ends are secured to their respective bucket reels 96 of the buckettransmission assembly 32. Rotation of the reels 96 raises the bucketfrom its forward low digging position as the rocker arms roll rearwardlyalong tracks 78 to an upward and rearward discharge position.

The bucket transmission 32 will be described with reference to FIGS. 2through 8.

The bucket reels 96 are keyed to the outer ends of cross shaft whichshaft is journalled for rotation in bearings 112 carried by thetransmission housing 116. Also keyed to the cross shaft is a large gearwheel 118. The gear 118 is in driving relation to gear 120 on theintermediate shaft 122. The intermediate shaft 122 is journalled inbearings 124 carried by the housing 116. Also rotatable with theintermediate shaft 122 is a bevel gear 125 and a stub shaft 126; thefunction of the latter shaft will be described with reference to thenovel power cutoff mechanism of the invention. A pinion gear 128 onshaft 130 engages the bevel gear 125. The pinion shaft is journalled inbearings 132 carried by the housing 116. Keyed to the forward end of thepinion shaft 130 is a brake disc 134 of a brake assembly generallydesignated 136.

A compound gear 138 having two sets of gear teeth 138' and 13$" is keyedto the pinion shaft 130 between the shaft support bearings 132. Gearteeth 133 are in constant mesh with the gear teeth of gear 140 and gearteeth 138" are in constant mesh with the gear teeth of gear 142.

Gear 140 and 142 are rotatably mounted on shaft 144, to the forward endof which is keyed the belt drum 38 hereinbefore described.

Alternate radially extending clutch discs of multiple disc clutch 146are secured to and rotate with gear 140'. The other discs of clutch 146are secured to the clutch housing 148, which housing is keyed to androtates with shaft 144. Within the clutch housing is a ring shapedpiston 150, spring urged out of engagement with the clutch discs. Therear portion 151 of the piston forms a presser plate for the clutchdiscs.

Pressure fluid is directed to the head of piston 150 through a conduit152, a portion of which is provided by an internal passage in the shaft144. If pressure fluid is directed into conduit 152 in the direction ofthe arrows in FIG. 4, the piston 150 urges the discs of clutch 146 intoengagement so that gear 140 will rotate with the clutch housing 148which is attached to shaft 144.

Alternate radially extending clutch discs of multiple disc clutch 154are secured to and rotate with gear 142. The other discs of clutch 154are secured to the clutch housing 156, which housing is keyed to androtates with shaft 144. Within the clutch housing 156 is a ring shapedpiston 158 spring urged out of engagement with the clutch discs. Therear portion 158 of the piston forms a presser plate for clutch discs.

Pressure fluid is directed to the head of piston 158 through conduit160, a portion of which is provided by an internal passage in the shaft144. If pressure fluid is directed into conduit 160 in the direction ofthe arrows in FIG. 3, the piston 158 urges the discs of clutch 154 intoengagement so that gear 142 will rotate with the clutch housing 156attached to shaft 144.

A third conduit 162, a portion of which is provided by an internalpassage in the shaft 144, supplies lubrication for the clutches,bearings and gears of the assembly. A pressure fluid return line 364connects the valve 164 and the transmission housing 32. The lubricatingoil and the pressure fluid are drained from the lowermost portion of thetransmission housing by return line 376 shown in FIG. 8 and to be morefully described hereinafter.

Conduits 152 and 160 are connected to a three spool pressure fluidcontrol valve 164. The valve 164 is connected to a source of pressurefluid, as to be more fully described hereinafter, through conduit 166.

Spool 168 of the valve is the high-speed low-speed selector spool and ismanually controlled by the machine operator through suitable controllevers, a portion of which is shown at 170. Valve spool 172 is a threeposition spool having a bucket hold center position, as shown in FIG. 8,a bucket up position as shown in FIG. 3 and a bucket down position whenthe spool is in its most inwardly position. Valve spool 174 is a twoposition spool which is automatically actuated by the bucket powercut-off mechanism.

The power cut-off mechanism, as more clearly shown in FIGS. 3-7,comprises a cam wheel 176 adjustabiy mounted on sleeve 173 secured toshaft 184 by means of plate 1&1) and nut 122. The shaft 184 has atapered serrated outer surface which matches internal serrations in thehub of sleeve 178. For the initial setting of the cam, the sleeve 178 isremoved from the shaft 184 and relocated for the approximate position onthe cooperating serrations. The final fine adjustment of thecam is madeby the set screws 176' carried by sleeve 178 and which bear against thecam 176. Thus by tightening one set screw and loosening the other, cam176 is rotated on sleeve 178 as more clearly shown in FIG. 7 of thedrawings. Reference indicia may be provided on the sleeve and the camwheel as shown at 186.

The shaft 184 is drivably connected to intermediate shaft 122 throughshaft 126, worm gear 183 secured thereto, and gear keyed to the shaft184. The ratio between the worm gear 188 and gear 191) is such that asthe bucket moves from a forward digging position to an elevated dumpingpostion the shaft 184 makes not more than one complete revolution.

A cam arm 1*)2, having a cam engaging roller 194 at one end is pivotallymounted to the housing 116 by bolt 196.

A lever arm 198 is also pivotally mounted at one end to the housing bybolt 196. The lever arm 198 is bifurcated at its other end.

Furcation 202 is connected to one end of valve spool 174 by means of aslot and pin lost motion arrangement 204, while the other furcation 200*is pivotally mounted at the head end of a cylinder 206.

A cylinder 208, having a smaller bore than cylinder 206, is slidablymounted within the cylinder 206. A piston 210, slidably carried onpiston rod 212, which extends axially through the piston, is slidablymounted in cylinder 206. A cap 207 screwed to the cylinder limits thetravel of piston 210 in a direction away from the cylinder head. Theinner end of pistonrod 212 is provided with a head portion 214 which isslidably mounted within the inner cylinder 208. A coil spring 216engages the base of the inner cylinder 208 at one end and the piston 210at the other end and urges the piston 210 and the cylinder 208 into anextended position substantially as shown in FIG. 5 of the drawings. Theouter end of piston rod 212 is pivotally connected to the cam arm 122 asat 218.

In operation of the novel bucket power cut-off mechanism, the cam wheel176 is rotated in the direction shown by the arrow as the bucket movesfrom a digging to a dumping position. As the bucket approaches thedumping position, cam arm 1112 is pivoted toward the cylinder 206. Theinitial movement of the cam arm rocks cylinder 206 and lever arm 1%downwardly which moves the valve spool 174 into a position as shown inbroken lines in FIG. 5. When the spool 174 reaches its position ofmaximum outward travel any further movement of cam arm 192 merelycompresses the spring 216 which permits the pistons 210 and 214 to slidewithin their respective cylinders. The pistons, cam, lever arm, andvalve spool are returned by spring 216 and spring 220 at the end ofspool 174 as to be more fully described hereafter.

When the shovel bucket returns from the dumping position to the diggingposition, cam wheel 176 rotates in a direction opposite to that shown bythe arrow in FIG. 5, moving the cam arm 192 away from the spool 174.With the spool in its innermost position, as shown in the drawing, allrearward movement of the cam arm 192 is taken up by coil spring 216 asthe cylinder 208 is urged away fromthe head of cylinder 206 against theforce of the spring.

The position of the bucket at the time the spool 174 cuts off power tothe bucket elevating transmission may be varied as hereinbefore pointedout by merely rotating the cam wheel 176 relative to the stub shaft 126.

A cycle of operation of the bucket transmission will be described inreference to FIGS. 3, 4 and 8 of the drawings.

A pump 222, driven by the prime mover 20, provides pressure fluid whichis directed by conduit 166 to the valve 164. Conduit 166 is preferablyprovided with a pressure gauge 351 and a check valve 353. The checkvalve 353 prevents the flow of pressure fluid in line 166 toward theconventional torque converter 22 which as disclosed in applicationSerial No. 377,125 is connected to the crawler drive mechanism. Thecheck valve 353 thus prevents pressure fluid from being robbed from theoverhead bucket transmission when the bucket is raising with a load andthe crawler clutches are operated to steer the machine or to reverse thedirection thereof. With the spool 1'72 in the position shown in FIG. 8,the bucket will not move as the ports controlled by this spool areclosed. Thus no pressure fluid can flow to conduits 152 and 160 or toconduit 224' which connects the valve 164 and the brake actuatingcylinder 226. The brake cylinder is spring urged into the brake onposition and the brake is released by pressure fluid forcing the piston227 into the brake release position against the force of spring 230within the brake release cylinder.

When the spool 172 is moved outwardly from its neutral position to thatposition shown in 'FIG. 3, pressure fluid flows through conduit 224 andreleases the brake 136 and a simultaneous flow of pressure fluid isdirected through the internal valve passages 228 and 229. At this pointthe position of valve spool 168 determines if the bucket is to be raisedby means of the high speed gear 142 or the low speed gear 140.

If high speed is desired, the spool 168 is moved inwardly to theposition shown in FIG. 3 and pressure fluid is directed to conduit 160and is vented from piston 150 through conduit 152 to the valve and thenthrough conduit 364 to the gear housing. Line 376 (FIG. 8) connects thegear housing 32 to the sump 284 from which the pump 222 sucks the liquidthrough conduit 386 and filter 388.

If low speed is desired, the valve spool is moved outwardly from theposition shown in FIG. 3 and the flow of pressure fluid in conduits 152and 169 is reversed.

When the bucket reaches a predetermined position, the cam actuated powercut-01f mechanism described above pulls valve spool 174 outwardly. Whenthe spool 174 is in its outermost position, flow of pressure fluidthrough internal valve passage 229 is cut off stopping the flow ofpressure fluid to the piston 150 or 158 whichever the case may be, andventing the fluid in the clutch to the sump line 364, disengaging thedrive to the bucket.

In order to prevent spring 220 from immediately returning the valvespool 174 to its original position the outward movement of the spool 174opens the passage 232 so that pressure fluid is directed through duct234 to the head of piston 236 which holds the spool 174 in the power otfposition and blocks the passage 232 to the sump line 364. With the valvespool in the above described position, the bucket is free to return tothe digging position by gravity.

The cam arm 192 and cam roller 194 are also held away from cam 176, sothat as the bucket returns by gravity to the digging position and thecam turns in the opposite direction to the arrow shown, plunger 174 cannot follow the cam movement and return pressure to the bucket clutch.The piston 236 holds the spool 174 out, permitting the bucket to fallfreely to the digging position.

In order to permit valve spool 174 to return to the position shown inFIGS. 3, 4 and 8, valve spool 172 is moved to its maximum inward orbucket down position or to the center or bucket hold position. Withspool 172 in either of these positions, the flow of pressure fluid tothe internal valve passage 229 is cut off which prevents the flow ofpressure fluid through duct 234 to the head of piston 236, thuspermitting spring 220 to return valve spool 174 to its normal position.The bucket may then be raised again by moving spool 174 out to thebucket up position.

Pump 222, besides supplying pressure fluid for the operation of thecrawler and bucket transmission, also supplies pressure fluid for thetractor torque converter 22, and lubricant for the crawler and buckettransmissions.

The pressure fluid from pump 222 passes through relief valve 355 whichprevents excessive pressures in the bucket transmission circuit. Therelief valve supplies fluid at pressure of about pounds per square inchto conduit 166 of the bucket transmission. The by-pass 357 from valve355 supplies pressure fluid to a second relief valve 359, which suppliespressure fluid at about 70 pounds per square inch through line 361 tothe torque converter 22. Fluid at any pressure in excess of 70 poundsper square inch is by-passed through line 363 to line 386 on the suctionside of pump 222. A drain line 365 for the torque converter is connectedto the sump line 376. The excess of pressure fluid supplied to thetorque converter is filtered by filter 371 provided with a by-pass valve372 normally set to open at a pressure of 20 pounds per square inch.

From filter 370, pressure fluid for lubrication is conducted by conduit374 to line 162, a portion of which, as hereinbefore described, isprovided by an internal passage in shaft 144 of the bucket transmission.Conduit 374 is provided with an orifice restrictor 367 to restrict theflow of lubricant to bucket transmission. An excessive flow of lubricantto the clutches of the bucket transmission has a tendency to cause adrag in the clutches resulting in a tendency to raise the bucket. Withpressure at about 70 pounds per square inch, and conduit 374 having adiameter of about 4 inch a .052 inch diameter orifice was found tomaintain flow at less than /2 gallon per minute which provided verysatisfactory results. The lubrication rafter seeping through thebearings, clutch discs and the like is conducted by sump line 376 to thereservoir 284.

From the foregoing description of the bucket transmission, it will beseen that the bucket brake mechanism is automatically applied when thebucket control spool 172 is released by the operator. The centeringspring 172' returns the spool 172 to the neutral position and in thisposition the pressure to the bucket brake cylinder 226 is evacuated andthe springs immediately apply to the brake, holding the bucket with itsload. Since the bucket brake is released by fluid pressure, it has beenfound that it is convenient to have a manual brake release in case ahydraulic line should break or if the prime mover should fail while thebucket is in the up position. In order to accomplish the manual releaseof the brake, levers 117 and 119 are suitably connected to a brakerelease handle not shown in the drawings.

The two speed bucket transmission provides a further multiplication ofthe torque advantage obtained by the combination of chain reels androcker arm shape. EX- tremely high digging force may be obtained in lowgear when the bucket is down in the digging position. As the bucket ismoving over to the discharge position, the operator may change thetransmission to high speed without dropping the load or slowing down thetravel of the bucket. The high speed drive then gives the maximumdischarge velocity to the bucket to throw the load a substantialdistance. However, if desired, the bucket may be left in the low speedrange and the bucket will discharge slowly for placing the load close tothe rear of the machine.

While only a preferred embodiment of the present invention has beendescribed in detail with reference to the drawings, it will be evidentto those skilled in the art that various modifications may be made inthe various components of the machine as defined in the appended claims.

This application is a continuation of our co-pending application SerialNo. 497,754, filed March 29, 1955 which is a continuation-in-part ofSerial No. 377,125, filed August 28, 1953, now Patent No. 2,843,213; andsimilar subject matter is disclosed and claimed in application SerialNo. 361,601, filed June 15, 1953, now Patent No. 2,792,140.

We claim:

1. A material handling machine including a material handling structure,dnive means for actuating said material handling structure, said drivemeans including a power source, a driven shaft, fluid pressure operatedclutch means between said power source and said driven shaft, a sourceof pressure fluid, means for selectively connecting the source ofpressure fluid and the fluid pressure operated clutch, means actuated bythe drive means for disconnecting the source of pressure fluid from thefluid pressure operated clutch and auxiliary pressure fluid actuatedmeans for holding said disconnecting means in the disconnecting positionafter said drive means has actuated said disconnecting means.

2. A material handling machine including an overhead material handlingstructure, drive means for actuating said overhead material handlingstructure from a low forward digging position to an elevated rearwardmaterial dumping position, said drive means comprising a motor drivenshaft, high and low speed gears drivably connected to said driven shaft,fluid pressure operated clutch means releasably connecting said highspeed and said low speed gears with said driven shaft, a source ofpressure fluid, means for selectively connecting the source of pressurefluid and the fluid pressure .operated clutches, a reel mounted forrotation on the machine, flexible draft me ans 1 connecting the reel andthe overhead material handling structure, a gear train connecting thereel and said high and low speed gears, a cam drivably connected to thegear train, a cam arm engaging said cam, means connected to said cam armfor disconnecting the source of pressure fluid from the fluid pressureoperated clutches said lastnamed means including a control valve havinga shiftable valve spool, and pressure fluid responsivetmeans forselectively maintaining the valve spool in the power-oif position.

3. The invention as defined in claim 2 including brake means for theoverhead material handling structure comprising a brake actuatingcylinder, l3. piston in said cylinder, spring means normally urging thebrake actuating piston into the engaged position, a fluid pressureconduit connecting the source of pressure fluid to the brake actuatingcylinder, valve means in said conduit controlling the flow of pressurefluid to and from said brake actuating cylinder.

4. A material handling machine including an overhead material handlingstructure mounted for rolling engagement from a low forward diggingposition to an upward and rearward dumping position, drive means foractuating said overhead material handling structure comprising a motordriven shaft, high and low speed gears rotatably mounted on said drivenshaft, fluid pressure actuated clutch means carried by said driven shaftreleasably connecting said high speed and said low speed gears to saiddriven shaft, a reel, a cross shaft rotatably mounted on the machine andconnected to the reel, flexible draft means connecting the reel and theoverhead material handling structure, a gear train including at leastone intermediate shaft connecting the said high and low speed gears tothe cross shaft, friction brake means operatively connected to saidshaft, said brake means including a brake actuating cylinder, a pistonin said cylinder spring urged into the brake engaged position, a sourceof pressure fluid, a pressure fluid control system comprising first,second and third pressure fluid control valves, conduit means connectingthe source of pressure fluid to said first control valve, conduit meansconnecting said first control valve with the brake actuating cylinderand the second control valve, conduit means connecting said secondcontrol valve with said third control valve, and conduit meansconnecting said third control valve with said clutch means carried bysaid driven shaft, and means connecting said drive means with saidsecond control valve for stopping the flow of pressure fluid to saidthird control valve.

5. The invention as defined in claim 4 wherein said means connectingsaid drive means to said second control valve comprises a cam drivablyconnected to said intermediate shaft, a cam arm engaging said cam, andmeans connected to said cam arm for actuating said second control valve.

6. A material handling machine including an overhead material handlingstructure, drive means for actuating said material handling structure,said drive means comprising a motor, a driven shaft, fluid pressureoperated clutch means between said driven shaft and said motor, a sourceof pressure fluid, valve means for selectively connecting the source ofpressure fluid and the fluid pressure operated clutch, a reel mountedfor rotation on the machine, flexible draft means connecting the reeland the overhead material handling structure, means drivably connectingsaid reel and said driven shaft, fluid pressure actuated brake means forsaid overhead material handling structure, conduit means connecting saidbrakemeans and said valve means whereby when said fluid pressureoperated clutch is engaged the brake is disengaged and when said clutchis disengaged said brake is engaged and pressure fluid flow controlmeans interposed between said valve means and saidclutch means fordisengaging said clutch means while said brake is disengaged, meansactuated by said driven shaft for moving the pressure fluid flow controlmeans to disengage the clutch means, and auxiliary pressure fluidresponsive means for holding said pressure fluid flow control means inthe clutch disengaged position.

7. The invention defined in claim 6 wherein said flow control means isactuated when the material handling structure is in the materialdischarge position.

References Cited in the file of this patent UNITED STATES PATENTS2,108,959 Brown Feb. 22, 1938 2,652,855 Wright Sept. 22, 1953 2,729,348Hackett et al. Jan. 3, 1956 2,752,053 Schwartz June 26, 1956

1. A MATERIAL HANDLING MACHINE INCLUDING A MATERIAL HANDLING STRUCTURE,DRIVE MEANS FOR ACTUATING SAID MATERIAL HANDLING STRUCTURE, SAID DRIVEMEANS INCLUDING A POWER SOURCE, A DRIVEN SHAFT, FLUID PRESSURE OPERATEDCLUTCH MEANS BETWEEN SAID POWER SOURCE AND SAID DRIVEN SHAFT, A SOURCEOF PRESSURE FLUID, MEANS FOR SELECTIVELY CONNECTING THE SOURCE OFPRESSURE FLUID AND THE FLUID PRESSURE OPERATED CLUTCH, MEANS ACTUATED BYTHE DRIVE MEANS FOR DISCONNECTING THE SOURCE OF PRESSURE FLUID FROM THEFLUID PRESSURE OPERATED CLUTCH AND AUXILIARY PRESSURE FLUID ACTUATEDMEANS FOR HOLDING SAID DISCONNECTING MEANS IN THE DISCONNECTING POSITIONAFTER SAID DRIVE MEANS HAS ACTUATED SAID DISCONNECTING MEANS.